Retailers are using increasingly sophisticated psychological techniques year-round to get you to stay longer, spend more and pick up products you didn't intend to buy, a CBC Marketplaceinvestigation reveals.

"Retail theorists started to realize that they really needed to do the work that casino theorists were doing," says marketing expert Brynn Winegard.

"Gambling is addictive. Well, so is shopping."

The full investigation, including what you need to know, airs Friday at 8 p.m. on CBC-TV and online.

According to a Marketplace survey, half of Canadians spent at least $100 on an impulse item they didn't budget for in the past year. And almost one in 10 of us spent at least $1,000 on a single impulse buy.

The average Canadian owes more than $21,000 in consumer debt, excluding mortgages, according to credit reporting agencies TransUnion and Equifax. Marketplace found that five per cent of us couldn't pay for basic needs because of impulse shopping.

Here are five tricky tactics you need to know before your next shopping trip:

1. Bigger carts lead to bigger spending

One reason your credit card bills may have increased: so has your shopping cart. Since the 1970s, shopping carts and baskets have grown dramatically, with some experts saying they have nearly tripled in size.

"For people trying to keep a budget, it's a problem," Winegard says. "The average amount of money that people make has not increased threefold."

People may spend more in stores because shopping carts and baskets have grown dramatically, with some experts saying they have nearly tripled in size. (CBC)

Why does it work? Because we're innately uncomfortable with empty space and feel the need to fill it up.

How to outsmart it: Just use your hands or grab the smallest cart or basket.

2. Mazes designed to confuse

Ever zigzagged through a big store, forgot what you came in for and then bought way more than you expected?

Confusing store layouts can cause you to lose focus and forget what you're looking for, which makes you more vulnerable to flashy marketing tricks. It's known as the "Gruen effect," named after Austrian architect Victor Gruen, who invented shopping malls.

"You also pretty soon lose any idea as to how far through the store you are, what the time duration is going to be," says Alan Penn, a professor of architectural computing at University College London.

When Penn studied Ikea's layout extensively, he found that when customers got distracted and disoriented by the maze layout, they were more likely to pick up cheap items along the way.

How to outsmart it: Stick to your list and resist the urge to browse.

3. Premium items up front, staples in the back

If you see pricier items when you walk into a store, don't be fooled. They're there to make you think you're getting a good deal on other products.

By the time you get past the artisanal cheeses that sit near the entrance of many grocery stores, that cheddar in the dairy case will seem cheap no matter what.

"It might still be $9 for a block of cheese, but it seems like nothing next to the sliver of Camembert you could get for $11.99," Winegard says.

How to outsmart it: Use a price-scanning app to help you make more informed decisions.

4. Playing up scarcity

Only two seats left on a featured flight deal? Faced with last-day sales, limited-time offers or while-quantities-last deals, many of us dig deep into our wallets. Most shoppers will buy impulsively if they fear missing out.

Supermarkets get in on the game, too, often limiting the number of a specific sale item customers can pick up.

"That will create a concept of scarcity in people's minds, so they'll be more likely to want to maximize to the limit," Winegard says.

That snap decision can come at a price. People tend to take bigger risks and act more impulsively when there's less time to make a decision.

Marketplace found that five per cent of us can't pay for basic needs because of impulse shopping. (CBC)

According to the Marketplace survey, sales are the No. 1 reason for making impulse purchases. The survey was conducted by EKOS in an online panel of 1,021 Canadians, between Oct. 30 and Nov. 4, 2015.

How to outsmart it: Take a deep breath. You probably don't need two bags of romaine lettuce. And that one-day, 40 per cent off sale is likely to be back in a few weeks.

5. Making you stay longer and spend more

The way stores sound, look and smell — it's all engineered to keep you in there.

When retailers offer free Wi-Fi or keep you fed, hydrated or caffeinated, they're trying to get you to stay longer. That may explain why large chains sometimes also have a fast-food outlet in the store and why you'll find coffee shops like Starbucks inside Chapters and Indigo bookstores.

And it's not just food. A 2010 study by the American Marketing Association found that supermarkets that play slower music increased sales by as much as 38 per cent.

"At some subconscious level, people have to rationalize to themselves why they spent so long in the store," Winegard says.

How to outsmart it: Plug in your headphones and shop to fast, upbeat music so you're in and out in no time.

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